Figures 15-21 in Oogenesis in Phragmatopoma (Polychaeta: Sabellariidae): Evidence for morphological distinction among geographically remote populations

Figures 15-21. Ultrastructure in Phragmatopoma caudata of the SW Atlantic. Grow Phase. Figures 15 and 16 Previtellogenic oocyte with a large nucleus (N) and nucleolus (Nu), as well as small rough heterochromatin clumps (small arrow). The cytoplasm is filled with rough, lamellar endoplasmic reticulum (RER) and noticeable mitochondria (M) in the perinuclear cytoplasm. The elongated portions of these cells create adhesion with adjacent oocyte (large arrow) (Figure 15, 2,050X. Figure 16, 4,200X). Oc = oocyte. Figure 17 Cytoplasm showing glycogen α (Gly) greater than the ribosomes (white arrows) attached to the reticulum (black arrow) (13,500X). M = mitochondria. Figures 18 and 19 Cortical cytoplasm of the rounded surface, showing Golgi complexes (GC) close to the cortical granules (CG), positioned beneath the microvilli (Mv) with the expansion bearing extensive filamentous adornment above the vitelline envelope (Eg) (Figure 18, 10,500x. Figure 19, 5,400X). Figures 20 and 21 Plasma membrane on a rounded surface showing endocytic depressions (black arrow) and coated vesicles (Cv). The vitelline envelope is composed by means of medium-apical extracellular matrix (2) in relation to microvilli (Mv). The basal region is electron-lucent and forming the beginnings of the perivitelline space (1) (Figure 20. 13,500X. Figure 21, 28,000X). GC = Golgi complexes, Eg = vitelline envelope.